Battery charging equipment

ABSTRACT

545,706. Charging batteries. STANDARD TELEPHONES &amp; CABLES, Ltd., and RICHARDS, E. A. Dec. 7, 1940, No. 17413. Addition to 516,135. [Class 38 (iv)] Relates to a system for maintaining a battery charged and preventing over-charge by introducing a resistance R1 by means of a thermal relay REL2 which is short-circuited, when the relay REL1 operates on the battery attaining full voltage, thereby re-inserting the resistance R1 for trickle charging as described in the parent Specification. The closure of the contacts REL1 also short-circuits a portion of resistance R2 in series with REL1 thus increasing the current through the relay and ensuring that the voltage must drop substantially before full re-charging is re-commenced as in the parent Specification. According to the present invention, in order to overcome the disadvantage introduced by this short-circuit connection that it renders the adjustment of the two relays interdependent, a rectifier MR, preferably a selenium cell, is inserted in the short-circuit connection to prevent flow of current from the junction of relay REL2 with R2 and the tapping point on the resistance R2.

Feb. 16, 1943. E. A. RICHARDS 2,311,574

BATTERY CHARGING EQUIPMENT Filed Nov. 8, 1941 rel] THERMAL RE]. A Y

REC BA T ,4.C. SUPPLY CONTACT VULTMETER-r gv uvvtwnm it/41W Patented Feb. 16, 1943 BATTERY CHARGING EQUIPMENT Edward Arthur Richards, London, England, assignor to International Standard Electric Corporation, New York, N. Y.

Application November 8, 1941, Serial No. 418,345

In Great Britain December 7, 1940 4 Claims.

This invention relates to a device for regulating the voltage of a secondary battery that is undergoing automatic charging.

We have already disclosed, in the specification of United Kingdom Patent No. 516,135, an aring trickle charge.

reliability.

this difiiculty.

the accompanying drawing.

arrangement of Fig. 1. tery BAT is a resistance RI.

R3 in series.

R4 across the battery BAT.

5 resistance R3, contacts rel I short circuit relay rangement in which a thermally-operated relay REL 2 and contacts rel 2 open to insert resistis connected across the battery that is underance RI into the charging circuit of battery BAT going charge so as to operate when the battery and reduce the charging rate to that of trickle voltage attains a predetermined maximum and charge. in operating to bring about circuit changes such of the rectifier MR, an adjustable point Q on that it will not release until the battery voltage resistance R2 is connected to the junction P befalls to a predetermined minimum. The functween relay REL 2 and resistance RI so that tion of the relay in relation to the charging is when contacts rel l are closed, part of resistance to introduce a resistance into the charging cir- R2 is short circuited and the relay REL I will cuit when it operates and to remove it on rere pe a until the Voltage across the lease, thus providing alternative trickle charge battery BA reaches a value several volts below and full charge respectively. However, as exthat at which the relay Operatedplained in the above-mentioned patent specifica- Owing, however. t0 the feet that the Voltage 0 tion, we found it desirable not to use the therthe junction point P between relay REL 2 a d many-operated relay directly by' means of resistance R4 is different from that of the point mally-closed contacts shunting the resistance; Q on resistance R2 to which P is Connected, a I but instead, to use a second relay controlled by current s through e y E I hich the first so that it is operative when the first remakes the adjustment of the upper and we lay i inoperative. i, during full charge and limits for the operation of relay REL I interdeis released when the first is operative, i. e., dur- P I thi manner t is possible In order to render these adjustments indeto make use of normally-open contacts for shunt: pendent of one another, a rectifier MR, P ing the resistance, as is desirable when dealing ably a Selenium rectifier, in rd e with with a heavy current, owing to their great the invention inserted as shown and prevent the flow of current between the junction P between In some cases this gives rise to the difiiculty relay REL 2 and resistance R4, and the djustthat the adjustments to determine the voltages 83318 point Q on resistance Whilst Still allowing at which the controlling relay operates and recontacts Tel I Shunt effectively a p O releases are not independent of one another. It is sistance R1 the object f th present i ti t remove The necessity for this arrangement arises from the fact that relay REL I, being a thermal relay, The nature of the invention will be better uns only one P o contacts. which must p derstood from th ll i description of one form the double function of short circuiting reembodiment thereof, taken in conjunction with 3 REL 2 and a portion of resistance R cordingly the invention is applicable to similar Referring to the drawing, Fig, 1 sh w an arrangement in which the relay REL I is of such rangement for charging a battery BAT from the a nature that it can have only one pair of concurrent derived from a rectifier REC, and Fig. 2 tacts, for p a Contact v tmete shows a modification i h may b made in the rangement in which the relay REL I is a contact I series it t tvoltmeter is shown in Fig. 2, wherein the contact c n t in Shunt l is on the moving arm of the voltmeter and the with the battery is a resistance R2, a hot-wire contact 2 is fixed. vacuum relay REL I and an adjustable resistance A lamp L is p o in Shunt of relay REL 2 A second hot wire vacuum relay to indicate when contacts rel I open and close,

REL 2 is connected in series with a resistance for the purpose of carrying out the adjustment.

What is claimed is:

During charging of the battery BAT at full 1. Adevice for regulating the automatic chargrate REL 2 is held operated and REL I is not ing of a secondary battery comprising: a resistoperated, the resistance R4 being such in relaance in the charging circuit shunted by a pair tion to R2 and R3 that the voltage across REL 2 is greater than across REL I. Contacts rel 2 are closed and short circuit resistance RI. When REL I operates, on the battery attaining a voltage determined primarily by the adjustment of Neglecting for the moment the presence An arof normally-open contacts, to furnish a full charging when the contacts are closed and a trickle charging when they are open; a relay for closing said contacts when it is operative, shunted by a pair of normally-open contacts so as to be operative when the contacts are open and released when the contacts are closed; a second relay for closing said second pair of contacts when it is operatively, connected across the battery in series with a resistance which is also shunted by said second pair of contacts, so as to operate when the battery attain a predetermined maximum voltage but to release only when the battery has fallen to a predetermined minimum voltage; and a rectifier in the connection betweenthe two relays which exists by reason of their common connection to one of the second pair of contacts.

2. A device for regulating the automatic charging of a secondary battery, comprising: a thermally-operated relay connected across the hat- 0nd thermally-operated relay connected so as to be operative whenever the battery is at a voltage demanding full-charge and having a single pair of normally-open contacts shunting a resistance in the charging circuit so that a full charge is delivered when the contacts are closed and a trickle charge when the contacts are open; the contacts of the first relay shunting the second relay and shunting a resistance in series with the first relay; and a rectifier in the connection between said contacts and the resistance.

3. A device as claimed in claim 1 in which said second relay is a thermally-operated relay.

4. A device as claimed in claim 1 in which said second relay is a contact voltmeter.

EDWARD ARTHUR RICHARDS. 

